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Fertilization system. The system of fertilization is based on techniques of applying mineral
and organic fertilizers in a crop rotation, at specified rates and times
According to [7], optimal rates of fertilizer application should be determined from data on nutrient
concentrations of the soil within each field. On fields where the actual concentrations of nutrients
in the soil are equal to optimal levels, there is no need to apply fertilizers. If concentrations of
nutrients within a specific field are lower than optimal, then the fertilizer rate is determined by
the method of elementary balance. Phosphate application rates are determined from its uptake by
desired crops and potassium application rates – by assessing the content of this nutrient in the soil.
Bacterial fertilizers can replace up to 30 kg/ha of active ingredient of nitrogen or phosphate
fertilizers.
Farm-yard manure applications to soil can be replaced by applications of cereal straw, maize stems
or green manure. They can support the same yields as farm-yard manure, but with 30.3% lower
rate of mineral fertilizers and up to 60% lower input of energy per 1 ha of the field area [7].
An improvement of irrigated soils can be achieved through the injection of fertilizers into the
irrigation system, i.e., fertigation. According to [15], fertigation can be carried out with the use of
soluble fertilizers (single and combined), which do not produce too much waste and do not cause
corrosion. They can be mixed with irrigation water in almost any proportions. The application
process is totally automatic, labour-saving and inexpensive. In situations where there are shortages
of organic and mineral fertilizers such resource-efficient methods of application are very important.
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Soil salinity manаgement manual | Part I.Soil salinity management in the Eurasian Region
For example, the use of a complex mineral fertilizer (so-called ‘tuk’) saves 30-50% of application
rates of, primarily, phosphates.
The application of fertilizers directly under plant roots has the following advantages:
• wasteful fertilizer losses are reduced by adding nutrients closer to the most active parts of root
systems and by mixing nutrients with a smaller volume of soil;
• processes of phosphorus and potassium immobilization (transformation of available forms
into unavailable forms) are less developed;
• coefficients of nitrogen and phosphorus uptake by plants are increased by 5-20% due to the
high nutrient availability.
The use of local raw materials and industrial wastes such as sapropels (rich organic sediments),
pond silt and lignin is a very important practice in the improvement of irrigated soils [7].
The use of green manure – a fertilizer consisting of growing plants that are ploughed back into
soil – is another important method of soil improvement. Plants that can be used as green manure
include the following: lupins, peas, white sweet clover, common vetch, oilseed radish, winter and
summer oilseed rape, rye, oats, trigonella, serradella, white mustard, etc. Leguminous plants are
more suitable for increasing the content of nitrogen in soil, while cereal crops are suitable for
improving soil structure and plant health.
In cases, when there is a deficiency in one or another nutrient in the soil, the application of
microfertilizers is practiced. Microfertilization can be achieved through small additions of mineral
fertilizers, application of dissolved fertilizers and pre-sowing treatment of seeds. The injection of
micronutrients (salts of copper, zinc, cobalt, molybdenum, etc.) into irrigation system results in
their uniform distribution over a field and generally improved crop growth [20].
Taking into account the shortage of mineral and organic fertilizers and the current state of
agriculture in Ukraine, it is suggested that the fertilization of irrigated soils should be conducted
as follows [7]:
• mineral fertilizers should be used only under priority crops to ensure their maximal agronomic
and economic efficiency;
• fertilizer rates should be determined depending on the agrochemical properties of soils
(nutrient availability levels for different crops during different stages of the growing season);
• fertilization systems should be economically efficient and use primarily local sources of
fertilizers, which ensure a high return of investment in crop yields;
• fertilizer application techniques, rates and time schedules should be determined on the
basis of previous fertilization practices (primarily the timing and rates of organic fertilizer
application in a crop rotation scheme);
• mineral fertilizers should be prioritized firstly for use on irrigated and chemically ameliorated
areas and secondly on formerly irrigated areas;
• potassium and chlorine-containing mineral fertilizers should not be used on soils affected by
irrigation salinity and alkalinity and residual salinity and alkalinity.
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Chapter 4.The rational use of saline and alkaline soils (with examples from Ukraine)
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